Why is my backend testimonial listing skewed

Testimonials

Per screenshot "testimonials widget backend skewed", the text in the backend is all vertical. The vertical text, is that way because there's not enough room to display it horizontally.

To fix, you need to deactivate some columns via Screen Options. See screenshot "testimonials widget screen options" for how.

Custom Bulk/Quick Edit

In order for fields to show up in QuickEdit, they're also added to the columns view. You can remove them from view by unchecking in Screen Options on the top right hand corner of your edit page view as above.